Reid and Prentiss go undercover to investigate a case of possible child abuse in an underground cult, when a federal raid goes south and they are taken hostage.
Desmond experiences unexpected side effects when he and Sayid hit turbulence on the way to the freighter.
The survivors begin to question the intentions of their supposed rescuers when four strangers arrive on the island.
Sawyer is forced to perpetuate his lie when some old friends drop in unannounced.
Sayid and Kate try to negotiate for Locke's hostage, whom they think might be the key to getting off the island.
